I'm using Premiere CS4 and am compiling a piece of footage from a 3D rendered scene I created, and sound I recorded. The source render file is 400 x 300. However, when I go to export the finished movie, also at 400 x 300, I get black borders on the left and right side of the movie which I don't want. I'm fairly new to Premiere so can anyone give me some ideas of why this is happening and how I can resolve it? I want to render out the final movie, at 400 x 300, the same resolution as the base 3D rendered file, without having those black borders there.

I've also noticed that I have those black side borders in the playback window in Premiere's interface too. I'm looking around for anywhere where the project settings differ to the clip size but don't see any, it seems to be 400 x 300 across the board. Any help greatly appreciated.

After a bit of research in Google, I believe the problem is to do with the Pixel Aspect Ratio (PAR). My 3D scene file has a PAR of 1.0 so I'm assuming the project settings in Premiere are different. Can someone tell me how to find the PAR for the project in Premiere?

After reading Craig's post above, a thought crossed my mind so I closed the current project and started afresh. This time, while setting up the project settings, I went into video and told the project to use Square Pixels 1.0 which I hadn't done before, I was using PAL 1.09... Now, when I placed my video on the Timeline, in the playback area in Premiere, the black borders are gone. SUCCESS!!!

But when I added in my sounds and then went to File -> Export -> Media, while the source preview is prefect, the Output has the black borders back. So I need to tell the exporter to use Square Pixels 1.0 too but I can't see any settings here to do that. So can someone tell me how to tell the Exporter to also use Square Pixels 1.0 as this movie is for playback on a computer, not television?